Wednesday, April 6, 2011

Giant prehistoric dinosaur cousin of T. rex identified

A giant predatory theropod dinosaur, similar in size and stature to Tyrannosaurus rex, has been identified by palaeontologists.

The new dinosaur, named Zhuchengtyrannus magnus, probably stood four metres tall, was 11 metres long and weighed around six tonnes.

Like T. rex, it was a carnivore with huge powerful jaws.

It ran on strong back legs, with puny front limbs, scientists report in the journal Cretaceous Research.

"There is no doubt that Zhuchengtyrannus was a huge tyrannosaurine," says Dr David Hone from University College in Dublin, Ireland, who led the team that discovered and named it.

"With only some skull and jaw bones to work with, it is difficult to precisely gauge the overall size of this animal.

"But the bones we have are just a few centimetres smaller than the equivalent ones in the largest T. rex specimen."

The newly discovered creature's name means "Tyrant from Zhucheng", as its bones were found in the city of Zhucheng, in eastern China's Shandong Province.

Tyrannosaurines are a specialised group of gigantic theropods - a group of dinosaurs that likely evolved into modern birds.

The dinosaur's jaws lower jaw and teeth revealed clues about its diet

They existed in North America and eastern Asia during the Late Cretaceous Period, which lasted from about 99 to 65 million years ago.

The group, which includes T. rex and its closest relatives, such as the Asian Tarbosaurus, were huge carnivores characterised by small arms, two-fingered hands, and large powerful jaws that could have delivered a bone-crushing bite.

They were likely both predators and scavengers.

However, Zhuchengtyrannus stands apart from other tyrannosaurines due to a combination of unique features in the skull not seen in any other theropod.

As well as a piece of lower jaw containing seven partly to fully erupted teeth, scientists found another piece of jaw bone containing eight teeth.

The size and character of the bones strongly suggest that the specimen was an adult.

For example, the teeth in the predatory dinosaur measure 10cm long.

Fossil flood

Among the international team of scientists involved in the study was Professor Xu Xing of the Beijing Institute of Vertebrate Palaeontology and Paleoanthropology in China, who has named more than 30 dinosaurs.

The skull and jaw bones were found in a quarry, which contains one of the largest concentrations of dinosaur bones in the world.

Most of the specimens recovered from the quarry belong to a gigantic species of hadrosaur, or duck-billed dinosaur.

Research suggests that the area contains so many dinosaur fossils because it was a large flood plain where many dinosaur bodies were washed together during floods and fossilised.